No rule is inviolate
I'm intentionally excluding Dungeon magazine adventures because I could easily triple this list with its goodness. It's hard to pick these as each brought new, iconic monsters and ideas!  Fixed editions, added more AD&D stuff, really a golden age of goodness.
- Isle of Dread: hexploration became awesome thanks to this one. You wanted to map every single hex and find every secret.  I may have played this under AD&D rules, but it's an oldie worth revising for any edition.
- Lost Caverns of Tsojcanth. Brilliant design, unique monsters. Set a standard.
- Ravenloft/House of Strahd: one of the best maps of all time and coolest villains ever.
- Dragons of Despair (Dragonlance): a chance to play your favorite book characters, and the Xak-Tsaroth map remains one of the best of all time. Maligned today as "railroad," it showed that "railroad" can and will sell. These adventures, combined with promotions, calendars, video games, recipe books, etc., launched a whole new way for TSR/D&D to do business.
- White Plume Mountain. Fantastical and memorable along with weapons that get everyone drooling.
- A Paladin in Hell. Pure epic idea, fantastic voyages to the darkest realms, and homage to the idea later in 5E's Avernus adventures.
- Return to the Tomb of Horrors. Brilliantly written and designed "return," making the old fresh with a set of mega-adventures around it all.
- Hidden Shrine of Tamoachan. Already recreated in 5E, brilliant way to start PCs at the "end" of the dungeon with a built-in timer (get out before the poison gas gets you.)
- Vault of the Drow. We get drow, the way they were meant to be.
- Tomb of Horrors. I ran this in every edition, but I always ran it to original form, hence the shout out. Challenge the way you design and think about dungeons. Gygax turned player expectation on its head and came up with a dungeon that couldn't easily be solved by hack-n-slash. Much debated, it's the most iconic module name in D&D history. One irony is that the finale, in the tournament version was completely avoidable, but players were conditioned that there's a big boss to fight.
- The Village of Hommlet. For design (dungeon, personalities, secrets), it's a model for how everything should be done for starter adventures.
- Slave Lords. Epic, should make you hate, hate, hate the slavers. However, dumping your PCs' hard earned treasure into the ocean after capture might get you strung up as a DM.
- The Assassin's Knot. First adventure I can recall with a timeline running behind a murder mystery with a cool area to search, can be linked to other stuff in the Lenore area but this one stood out.
- Red Hand of Doom. The best way I've ever seen written to handle a restricted sandbox invasion adventure. Just so well done.
- Sunless Citadel. Near-perfect dungeon crafting for a starter-level group, and Meepo.
- Kingmaker: hexploration returns with unique (albeit too complex) kingdom building rules. With a lot of help, this one became the best campaign I've ever DMed. Thanks to Paizo forums, you have all the pre-written help you'll ever need for those ideas.
- Skulls & Shackles, Carrion Hill, et al: I lump the Pathfinder "series of 6" modules because they're all decent, but they're decent because you gradually got your adventures with time for others to offer ideas on active forums, find what other DMs are doing, find what other players are doing, talk to the game designers (who are active on their forums) before and after modules come out, and they came with optional accessories like maps. The only downside is that some writers are better than others, and it can show when modules come out. As an example, one author had a lot of material cut for space in a Kingmaker module. He provided all this material to gamers, freely. 100% awesome. You never found that kind of interaction with D&D.
- Curse of Strahd. Like Kingmaker, it needs fleshed out, and the personality of Strahd redone to match his literary ("I, Strahd") version. Otherwise, brilliant successor to the original.
- Lost Mines of Phandelver. It worked on every level to capture that original feel of exploring the unknown and finding secrets behind every rock. And a dragon. Great for bringing in new folks to D&D.